A copy of a spell can be countered like any other spell, but it must be countered individually. Countering a spell with replicate won't affect the copies.
2024-06-07
Triggered abilities use the word "when," "whenever," or "at." They're often written as "[Trigger condition], [effect]." Some keywords (such as prowess) are triggered abilities and will use "when," "whenever," or "at" in their reminder text.
Replicate (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Counter target triggered ability or colorless spell.
(When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)